Assignment
Part I:
1. The following is the C# sample code that shows two threads use mutex to communicate. Note mutex is a simplified semaphore.
Refer to this piece of sample code, write a program that conduct the followings:
(1) It contains two thread, t1 and t2;
(2) t1 and t2 share a variable, myNum;
(3) When myNum is empty (use 0 to show empty), t1 will generate a random number between 1 and 99, and save to myNum;
(4) When myNum is not empty, t2 will get this number and save it to an array, myNumArray, in ascending order.
(5) After t2 insert a new number in myNumArray, it also shows the result on screen.
// mutex sample code
using System;
using System.Collections.Generic; using System.Linq;
using System.Text; using System.Threading;
class Test
{
// Create a new Mutex. The creating thread owns the
// Mutex.
private static Mutex mut = new Mutex(true); private const int numIterations = 1; private const int numThreads = 2;
static void Main()
{
// Create the threads that will use the protected resource. for (int i = 0; i < numThreads; i++)
{
Thread myThread = new Thread(new ThreadStart(MyThreadProc)); myThread.Name = String.Format("Thread{0}", i + 1); myThread.Start();
}
// Wait one second before allowing other threads to
// acquire the Mutex.
Console.WriteLine("Creating thread owns the Mutex."); Thread.Sleep(1000);
Console.WriteLine("Creating thread releases the Mutex.\r\n"); mut.ReleaseMutex();
//Console.ReadKey();
}
private static void MyThreadProc()
{
for (int i = 0; i < numIterations; i++)
{
UseResource();
}
}
// This method represents a resource that must be synchronized
// so that only one thread at a time can enter. private static void UseResource()
{
// Wait until it is safe to enter. mut.WaitOne();
Console.WriteLine("{0} has entered the protected area", Thread.CurrentThread.Name);
// Place code to access non-reentrant resources here.
// do work here!! Thread.Sleep(500);
Console.WriteLine("{0} is leaving the protected area\r\n", Thread.CurrentThread.Name);
// Release the Mutex. mut.ReleaseMutex();
}
}
Part II: Login to Linux (Hyper-v Virtural machine), study Linux and following the following questions.
1. Which of these is a UNIX command which will list the contents of a directory?
A. pwd
B. ls
C. list
D. files
E. directory
2. To make a new directory, you would use which command?
A. directory
B. create
C. make
D. mkdir
E. dirmk
3. To remove a directory, you would use which command?
A. remove
B. erase
C. delete
D. deldir
E. rmdir
4. The command which terminate a process is called:
A. copy
B. file
C. filecopy
D. cp
E. kill
5. Partial output of ls -F command is: Work1*
Work2/
Which of the following is correct?
A. Work2 is executable, Work1 is a directory
B. Both are executable
C. Work1* and Work2/ are two files
D. Work1 is executable, Work2 is a directory
E. None of above
6. To check the process status, which command you would use:
A. ps
B. left
C. cat
D. quotas
E. disk
7. The command, makedir, will create a sub-directory. True or false?
A. True
B. False
8. is the command that changes the file permission.
A. pr
B. top
C. chmod
D. head
10. The command will display the absolute pathname for the directory that you are wokring in.
A. dir
B. whereami
C. pwd
D. ls
11. In Fedora 20, a regular user, john, wants to become root user and do some administration tasks. Which of the following should he use?
A. root
B. super
C. admin
D. su root
12. In Fedora 20, which of the following display process state dynamically?
A. ps
B. top
C. more
D. cat
13. In Fedora 20, a regular user, john, wants to check whether a program, DemoApp, is running or not. Which of the following should he use?
A. find DemoApp
B. whereis DemoApp
C. man DemoApp
D. ps -ax
14. In Fedora 20, a regular user, john, wants to check the options for ps command. He type man ps
Which of the following will terminate man command?
A. c
B. q
C. x
D. z